1. Field of the Invention
This invention relates, in general, to a barcode scanning device for reading coded information such as a barcode. In particular, the invention relates to a method and apparatus for forming scanning lines in a wide range and forming a high-density scanning pattern by increasing the number of scanning lines in a key area within the range.
2. Description of the Related Art
Conventionally, there have been known a barcode scanning device having a read window in front capable of reading a barcode affixed to a commodity by scanning light transmitted through the read window.
For example, U.S. Pat. No. 6,581,832 discloses a barcode scanning device comprising a read window, a light source, a reflecting mirror, a polygon mirror, and a group of fixed mirrors. In this barcode scanning device, a light beam emitted from a light source is reflected by a polygon mirror and a group of fixed mirrors, and is output through a read window as scanning light.
This scanning light forms a scanning pattern consisting of three horizontal scanning lines, a scanning pattern consisting of symmetrical cross-lines each side of the pattern having three scanning lines (total of six lines), and a v-shaped scanning pattern having lines steeper than those of the cross-line pattern each consisting of three scanning lines (total of six lines).
A disadvantage of the above barcode scanning device is that, because the three scanning lines of the respective scanning patterns are equally spaced, when a commodity is held being tilted from a plane in parallel with the read window, the lines of the scanning patterns formed on a commodity become sparsity.
Particularly, when a commodity is held so that a surface of a barcode affixed to the commodity is positioned in substantially vertical position relative to the read window, the reading performance of the barcode remarkably degrades.
Therefore, such a barcode scanning device is not suitable to the use for reading barcodes of commodities whose contents tend to be crumbled in shape when inclined, for example, those packed in a tray such as fishes, meat, and precooked foods.